1. Field of the Invention
Apparatuses, systems and methods consistent with the present invention relate to representing a color image on a display having a stripe arrangement structure, and more particularly, to reducing color error caused by the use of a pixel rendering method on a display having a stripe arrangement structure to represent an optimum color image.
2. Description of the Related Art
As shown in FIG. 1, a general image display device requires three sub-pixels, i.e., R, G, and B sub-pixels, to represent a pixel. Thus, the general display device separately manipulates the three sub-pixels to theoretically increase a horizontal resolution of a stripe structure shown in FIG. 1 three times. Also, when a high resolution image is displayed in a low resolution display device, a general pixel rendering method generates jagged patterns at the boundaries of minute letters such as italics. The jagged patterns may be reduced by sub-pixel rendering, i.e., separately manipulating sub-pixels. However, the sub-pixel rendering generates a false color rendering at a curved or oblique boundary of an image. A vertical color error may occur at a vertical edge of an image on a display having a sub-pixel structure. These two types of color errors are generated by a sharp change of a brightness value between neighboring sub-pixels. In the case where sub-pixels are arranged in a stripe structure, the two types of color errors may frequently occur in a diagonal or vertical representation.
A conventional method of representing a high resolution input signal on a low resolution display will now be described with reference to FIG. 2.
Referring to FIG. 2, an input signal includes a plurality of pixels each including three sub-pixels as described with reference to FIG. 1. As described with reference to FIG. 1, the three sub-pixels are sub-pixels “R,” “G,” and “B.” As an example, six pixels are shown in FIG. 2. The six pixels are pixels “0” through “5.” Thus, the first pixel includes sub-pixels “R0,” “G0,” and “B0”, and the second pixel includes sub-pixels “R1,” “G1,” and “B1.” The fifth pixel includes sub-pixels “R4,” “G4,” and “B4,” and the sixth pixel includes sub-pixels “R5,” “G5,” and “B5.”
A resolution of a display is ⅓ of the resolution of the input signal. Thus, the resolution of the input signal is reduced to ⅓ to represent the input signal on the display. To reduce the resolution of the input signal to ⅓, one of sub-pixels of the pixels of the input signal is selected, and a pixel is represented by the selected sub-pixel. For example, referring to FIG. 2, the sub-pixel “R0” is selected from the first pixel of the input signal to represent the sub-pixel “R0” as the first pixel on the display, and the sub-pixel “G0” is selected from the first pixel to represent the sub-pixel “G0” as the second pixel on the display. Also, the sub-pixel “B0” is selected from the first pixel of the input signal to represent the sub-pixel “B0” as the third pixel on the display, and a sub-pixel “R3” is selected from the fourth pixel of the input signal to represent the sub-pixel “R3” as the fourth pixel on the display. A sub-pixel “G3” is selected from the fourth pixel of the input signal to represent the sub-pixel “G3” as the fifth pixel on the display, and a sub-pixel “B3” is selected from the fourth pixel of the input signal to represent the sub-pixel “B3” as the sixth pixel on the display.
FIG. 3 illustrates another method of representing a high resolution input signal on a low resolution display. Referring to FIG. 3, a sub-pixel “R0” is selected from a first pixel of an input signal to represent the sub-pixel “R0” as the first pixel on a display, and a sub-pixel “G1” is selected from a second pixel of the input signal to represent the sub-pixel “G1” as the second pixel on the display. Also, a sub-pixel “B2” is selected from a third pixel of the input signal to represent the sub-pixel “B2” as the third pixel on the display, and a sub-pixel “R3” is selected from a fourth pixel of the input signal to represent the sub-pixel “R3” as the fourth pixel on the display. A sub-pixel “G4” is selected from a fifth pixel of the input signal to represent the sub-pixel “G4” as the fifth pixel on the display, and a sub-pixel “B5” is selected from a sixth pixel of the input signal to represent the sub-pixel “B5” as the sixth pixel on the display.
While the methods described with reference to FIGS. 2 and 3 are effective for improving resolution, they increase the color error caused by sub-pixel rendering.
FIG. 4 illustrates color error caused by conventional rendering. As described above, sub-pixels are arranged in stripe structures and in the order of R, G, and B. A color error, which occurs between pixels according to the prior art, occurs between sub-pixels due to an increase in size of the pixel on a display having a stripe structure. Referring to FIG. 4, according to pixel unit rendering, brightness is increased by “B” on the left side of “T,” and brightness is sharply increased by “R” on the right side of “T.” Thus, a color error occurs. The boundary becomes unclear due to the color error.
Accordingly, a method of reducing a color error occurring between sub-pixels using pixel rendering is required.